There are many modern Chinese claiming to have some long-lost lineage of Vajrayana, most of whom are frauds.

I agree on this and back on the now defunct E-Sangha, there was a discussion in the East Asian Buddhism Forum on what was regarded as an authentic and low profile group known as the 唐密 Táng Mì

On another note... I find this somewhat in my estimation the most beautiful definition on Tantra (Vajrayana) practice by HHDL...

Jeffrey Hopkins's Meditation on Emptiness, Page 111Tantra is limited to persons whose compassion is so great that they cannot bear to spend unnecessary time in attaining Buddhahood, as they want to be a supreme source of help and happiness for others quickly

And on fascination with siddhis...Then Kevatta the householder approached the Blessed One and, on arrival, having bowed down, sat to one side. As he was sitting there he said to the Blessed One: "Lord, this Nalanda is powerful, both prosperous and populous, filled with people who have faith in the Blessed One. It would be good if the Blessed One were to direct a monk to display a miracle of psychic power from his superior human state so that Nalanda would to an even greater extent have faith in the Blessed One."

When this was said, the Blessed One said to Kevatta the householder, "Kevatta, I don't teach the monks in this way: 'Come, monks, display a miracle of psychic power to the lay people clad in white.'"

A second time... A third time, Kevatta the householder said to the Blessed One: "I won't argue with the Blessed One, but I tell you: Lord, this Nalanda is powerful, both prosperous and populous, filled with people who have faith in the Blessed One. It would be good if the Blessed One were to direct a monk to display a miracle of psychic power from his superior human state so that Nalanda would to an even greater extent have faith in the Blessed One."

A third time, the Blessed One said to Kevatta the householder, "Kevatta, I don't teach the monks in this way: 'Come, monks, display a miracle of psychic power to the lay people clad in white.'

"Kevatta, there are these three miracles that I have declared, having directly known and realized them for myself. Which three? The miracle of psychic power, the miracle of telepathy, and the miracle of instruction.Read on here